php - 在wordpress中选择没有类别的帖子

我有一个从特定类别中选择列表的脚本:

SELECT wp_posts.*
  FROM wp_posts
       LEFT JOIN wp_term_relationships
                 ON wp_posts.ID=wp_term_relationships.object_id
       LEFT JOIN wp_term_taxonomy
                 ON wp_term_taxonomy.term_taxonomy_id = wp_term_relationships.term_taxonomy_id
       LEFT JOIN wp_terms
                 ON wp_terms.term_id = wp_term_taxonomy.term_id
 WHERE wp_posts.post_type = 'post'
   AND wp_posts.post_status = 'publish'
   AND (
            wp_term_taxonomy.taxonomy = 'category'
        AND wp_term_taxonomy.term_id = wp_terms.term_id
        AND wp_terms.name = '$category'
       )

如何选择未分类的帖子？我尝试了 $category = '' 并得到了 0 行，因为 wp_terms.name ='' 没有字段。

最佳答案

您可以使用 where id is null 子句来要求 left join 未成功:

SELECT  p.*
FROM    wp_posts p
LEFT JOIN
        wp_term_relationships rel
ON      p.ID = rel.object_id
LEFT JOIN
        wp_term_taxonomy tax
ON      tax.term_taxonomy_id = rel.term_taxonomy_id
        AND tax.taxonomy = 'category'
LEFT JOIN
        wp_terms term
ON      term.term_id = tax.term_id
WHERE   p.post_type = 'post'
        AND p.post_status = 'publish'
        AND term.term_id is null -- No category found

可以使用 not exist 子句来完成相同的操作:

SELECT  *
FROM    wp_posts p
WHERE   p.post_type = 'post'
        AND p.post_status = 'publish'
        AND NOT EXISTS
        (
        SELECT  *
        FROM    wp_term_relationships rel
        JOIN    wp_term_taxonomy tax
        ON      tax.term_taxonomy_id = rel.term_taxonomy_id
                AND tax.taxonomy = 'category'
        JOIN    wp_terms term
        ON      term.term_id = tax.term_id
        WHERE   p.ID = rel.object_id
        )

关于php - 在wordpress中选择没有类别的帖子，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21749464/